


Rotten Edgeberry

by Canadian_BuckBeaver



Category: Undertail - Fandom, Undertale (Video Game)
Genre: Alternate Universe - Underfell (Undertale), Blood and Gore, Character Death, Crossover Pairings, Established Relationship, Fellcest - Freeform, Fontcest, Infection, Jealousy, M/M, Non-Consensual Voyeurism, Punishment, Royal Guard Papyrus (Undertale), Underfell Doggo - Freeform, Underfell Grillby (Undertale), Underfell Papyrus (Undertale), Underfell Sans (Undertale), Underswap Sans (Undertale), Unhealthy Relationships, Unrequited Crush, Yandere Sans (Undertale), edgeberry, messed up
Language: English
Status: Completed
Published: 2018-11-17
Updated: 2018-11-17
Packaged: 2019-08-25 01:24:17
Rating: Mature
Warnings: Graphic Depictions Of Violence, Major Character Death
Chapters: 1
Words: 949
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16651630
Author URL: https://archiveofourown.org/users/Canadian_BuckBeaver/pseuds/Canadian_BuckBeaver
Summary: One night, afer a rough day, Sans of Underfell returns home to see a nightmare





	Rotten Edgeberry

Red grumbled as he closed the door behind him, walking into the dark house. It had been another terrible day in the dust-filled world of UnderFell. There were a few more inconspicuous dust piles under the Christmas Tree in Snowdin to start. While he was stuck at his sentry station, Doggo never showed up for his shift. And then, while at Grillby’s bar, one of the regular patrons had gotten a little too handsy for his liking, so Sans removed them. It wasn’t until the monster had dusted from blood loss that Sans had realized that it was a guard from Papyrus’ platoon. A royal guard, dead by his hands. A major mistake, one that had made his marrow run cold at the thought.

Though, the more Sans thought of it as he stomped the mixture of dust and snow from his shoes, the less upset that he thought Boss would be. The guard was not acting as a guard should and, “anyone who takes their breaks at Grillby’s”….there was a pair of bright blue eyes staring at him.

With a snarl, Sans instantly summoned two large Gaster Blasters, both positioned in front of him. Able to fight and defend. The magic that gathered in their jaws glowed white, illuminating the small skeleton’s face in front of him.

“God damnit Blue, I could have killed ya,” he snapped, dismissing the magic before the weapons could fire.

The eyes seemed to shrug. “You never came home, Red,” the skeleton simply said. “Someone needed to watch for you.”

He never got what Boss saw in the small, innocent and energetic skeleton. They both loved puzzles and were driven to their goals, yes, but the little Swap monster was as different as Boss as the night was from day. Blue always seemed to know when Sans definitely did not want to see him.

“So you decided to sit in the room, alone and in the dark? Real fucking smart.” Sans snapped.

There was a small giggle and some of the sparkle came into those blue eyes. “Who says that I was alone?”

A small light clicked on suddenly, lighting the room in dim light. Red took quick step back, eyes widening as the light uncovered the horrors that hid in the dark. Doggo was behind the couch, tied up like a tousled turkey. Long, deep slashes covered the monster’s body, the fur peeling away from the tissue, and that rotting smell. He had to be missing for more than a day to smell like that.

And Boss, the Papyrus of Underfell, was resting his head in Blue’s lap, hands wrapped around his waist. He was purring, perfectly content to sit there, submissive to the small monster. And Blue sat in that damn armchair like a throne, his hands tenderly stroking Edge’s skull. The pose reminded Sans of a picture he had once seen in the throne room, one of Asgore and Toriel.

How and why….

And that aura. It was cold and dark, something not even himself had felt before.

He allowed a choked chuckle to escape his teeth. “Well, I have'ta say you managed to surprise me. But I have a date with my bed so…” he quickly turned to leave.

“I’ve seen the way you look at him.”

That caused Sans to pause as a shiver ran down his spine. “I’m sorry?” Sans asked.

Blue’s eyelights latched onto him. “I’ve seen the way you look at your brother,” he said again, his fingers stilling. “You don’t think I’m worthy of him, do you?” Edge’s eyes slowly opened, looking up at Blue.

Sans tried to get his breathing under control. “Blue, he’s my brother. No one in my mind is good enough for him. Not you, not MTT, not even Asgore…”

“But you are?”

Oh shit. Sans took a deep breath and dared himself to look into those eyes. “Of course not. I am his brother, his old protector, nothing more.”

Blue nodded distractedly, again rubbing Edge’s skull, making the taller monster purr. “Doggo was watching as Edge and I had relations,” he said to Sans, nodding at the dog monster. “He attempted to get on the action too but, on my order, Edgie did not kill. We decided to keep him just barely alive, let him think about his actions.”

“I don’t really think that it is appropriate to be talking about this-” Sans started, only to be silenced by a look from Blue.

“But I’ve seen the way you look at him. You look at him the same way that I do, the same way that Queen Toriel looks at Asgore when she thinks no one watches.” Those blue eyes narrowed at him, making Sans quake ever so slightly.

“Blue…”

“We are very open with each other,” Blue spoke over him, scratching under Edge’s chin. “I told him that I didn’t like the way you looked at him, the ways that you tried to convince me that I wasn’t good enough for him.” His fingers stopped moving then and Edge’s eyes snapped open.

Sans took a step back. “I have no idea what you’re-”

“So I asked him to get rid of the problem. One or the other, but he couldn’t have both.”

Sans’ eyelights widened and he began to growl, stepping into his typical stance, good for attack or defense. “He wouldn’t dare…”

Edge was missing from Blue’s lap.

There was a cold, dark presence behind him. As Sans slowly turned, he saw his brother standing over him, bone sword raised and eyelights blazing in fury. “Papyrus?” He asked, a cold sweat running down his skull.

The bone sword fell, slicing through bone and marrow like butter.

**Author's Note:**

> A request from my Tumblr!


End file.
